Cast iron is used in making

Analyze the question: The question asks what cast iron is used for. This is about the types of iron and their properties.

Explain the concept: Iron comes in three main forms, depending on its carbon content:

• Cast iron (about 2-4% carbon): It is hard but brittle. It cannot be hammered or stretched, but it melts easily and can be poured into moulds. It also holds heat well.
• Wrought iron (almost no carbon, below 0.25%): It is soft, malleable and ductile. It is used for things that must bend or be shaped without breaking.
• Steel (0.25-1.5% carbon): It is strong and tough. It is used for construction, tools and machinery.

Solution: Compare each option with the properties of each type of iron:

• A. Chains and agricultural implements: Chains need toughness and flexibility, which brittle cast iron lacks. These are made from wrought iron or steel.
• B. Iron sheets and retort stand: Sheets must be rolled out thin, which needs malleable metal such as mild steel. Cast iron would crack.
• C. Nails and iron rods: Nails and rods need to be drawn or hammered into shape, so they are made from wrought iron or mild steel.
• D. Stoves and cookers: These parts are cast in moulds. They must withstand high heat, and cast iron does this well. It is also cheap and easy to cast into shape.

Answer: Cast iron is used for stoves and cookers, which is option D.

Tip: Remember "Cast = Cooker". Cast iron is cast (poured) into moulds, so it is used for fixed shapes like stoves, cooking pots, gas cookers, manhole covers and engine blocks. Anything that must be bent, stretched or hammered (nails, chains, sheets) is not cast iron.